What is vitamin K?

Vitamin K is a fat-soluble vitamin essential for various bodily functions, particularly blood clotting and bone health.

It is vital for the activation of several proteins necessary for these processes, including those involved in blood clotting, bone metabolism, and maintaining proper calcium balance.

Without adequate vitamin K, the body cannot efficiently perform these crucial functions, leading to potential health issues.

Sources of Vitamin K

There are two primary forms of this vitamin: phylloquinone (K1) and menaquinones (K2). These forms are found in different sources and play unique roles in the body.

K1 is abundant in plant-based foods, especially leafy green vegetables like kale, spinach, and broccoli.

These greens are not only rich in this nutrient but also provide other essential nutrients like fiber, vitamins A and C, and iron. 

Other sources of K1 include Brussels sprouts, asparagus, and avocado, although in smaller amounts. 

Incorporating these foods into your diet can significantly boost your K1 intake.

K2, on the other hand, is present in fermented foods such as cheese and natto, a traditional Japanese dish made from fermented soybeans.

It is also found in animal-based products like eggs and meat. Additionally, the bacteria in our gut produce K2, which further contributes to our overall levels.

K2 has a longer half-life in the body compared to K1, meaning it stays in the bloodstream longer and may be more effective at activating proteins involved in bone metabolism.

This makes fermented foods and certain animal products important for those looking to boost their K2 levels.

Role in Blood Clotting and Bone Health

This vitamin plays a critical role in blood clotting, a process essential for repairing damaged blood vessels and preventing excessive bleeding.

When a blood vessel is injured, platelets and clotting factors collaborate to form a blood clot that stops the bleeding.

Adequate intake is necessary for the activation of several clotting factors, including prothrombin, which is essential for the formation of a blood clot.

Without sufficient levels, the body cannot effectively activate these clotting factors, leading to prolonged bleeding or easy bruising.

The activation of clotting factors occurs through a process known as carboxylation, where a chemical group called a carboxyl group is added to certain proteins.

This modification allows the proteins to bind calcium ions, which are crucial for their proper function in blood clotting.

Without adequate intake, this process is impaired, and clotting factors cannot function correctly, increasing the risk of bleeding.

Why Take Vitamin K?

People take supplements for various reasons. Those on blood thinners (anticoagulants) may be advised to take this vitamin to maintain proper blood clotting function.

Blood thinners work by inhibiting the action of this nutrient, so supplementation can help balance this effect and prevent excessive bleeding.

However, it's crucial for individuals on blood thinners to manage their intake carefully and under medical supervision to avoid interfering with their medication.

Supplements may also be recommended for individuals with a deficiency or those at risk of a deficiency.

People with malabsorption disorders, such as Crohn's disease or celiac disease, may have difficulty absorbing fat-soluble vitamins like this one, leading to a deficiency.

Similarly, individuals who have undergone weight loss surgery, such as gastric bypass, may experience reduced absorption of nutrients, including this one.

In these cases, supplements can help ensure adequate levels and prevent complications associated with deficiency.

Benefits of Vitamin K

The primary benefit of this vitamin is its role in blood clotting.

Adequate intake ensures the proper activation of clotting proteins like prothrombin, preventing excessive bleeding and easy bruising.

This is particularly important for individuals with bleeding disorders or those taking anticoagulant medications.

Ensuring sufficient intake can help maintain the delicate balance required for effective blood clotting.

This nutrient also supports bone health by aiding in the deposition of calcium into bones.

This process strengthens the bones and helps prevent osteoporosis.

Research has shown that individuals with higher intake have better bone density and a lower risk of fractures, highlighting the importance of this vitamin for long-term skeletal health.

Additionally, it may offer other health benefits. Some studies suggest it has anti-inflammatory properties, which could benefit individuals with inflammatory conditions such as eczema.

It may also play a role in the proper functioning of the immune system, helping the body fend off infections and maintain overall health.

Furthermore, this nutrient is essential for maintaining healthy skin, potentially reducing the appearance of dark circles and improving skin elasticity.

Emerging research indicates that adequate intake may reduce the risk of heart disease.

One study found that individuals with higher levels had a lower risk of heart disease and stroke compared to those with lower levels.

Another study suggested that supplements might help reduce arterial calcification, a condition where calcium deposits build up in the arteries, increasing the risk of heart disease.

By preventing calcification, this vitamin can help maintain arterial flexibility and support cardiovascular health.

Vitamin K Dosage for Different Ages

Vitamin K is an essential fat-soluble vitamin that exists in two main forms: phylloquinone (K1) and menaquinones (K2).

Phylloquinone is primarily found in green leafy vegetables, while menaquinones are present in fermented foods and animal products.

This vitamin plays a crucial role in blood clotting and bone metabolism. Below are the recommended daily intakes for vitamin K across different age groups: [4]

Infants

0–6 months: 2.0 micrograms (mcg)
7–12 months: 2.5 mcg
For infants, the adequate intake (AI) levels are based on the vitamin K content in breast milk and the assumption that newborns receive prophylactic vitamin K at birth to prevent bleeding disorders.

Children

1–3 years: 30 mcg
4–8 years: 55 mcg
9–13 years: 60 mcg
These levels ensure adequate growth and development, supporting both bone health and the proper functioning of blood clotting mechanisms.

Adolescents and Adults

14–18 years (boys): 75 mcg
14–18 years (girls): 75 mcg
19 years and older (men): 120 mcg
19 years and older (women): 90 mcg
Adolescents and adults have different requirements due to changes in body size and metabolic needs. The higher intake for adult men reflects their generally larger body size compared to women.

Pregnant and Lactating Women

Pregnant women (19 years and older): 90 mcg
Lactating women (19 years and older): 90 mcg

Pregnant and lactating women need sufficient vitamin K to support their health and the development of their babies.

The recommended intake helps maintain proper blood clotting and bone health during these critical periods.

Signs of vitamin K deficiency

Although relatively uncommon, deficiency can occur in certain individuals, particularly those with conditions affecting nutrient absorption.

Malabsorption disorders, such as Crohn's disease or celiac disease, can impair the body's ability to absorb fat-soluble vitamins, including this one. 

This can lead to a deficiency, with symptoms such as easy bruising, prolonged bleeding after cuts or injuries, and heavy menstrual periods.

Individuals who have undergone weight loss surgery, such as gastric bypass, may also be at risk of deficiency.

These procedures can reduce the body's ability to absorb nutrients, including this one.

Monitoring nutrient levels and ensuring adequate intake through diet or supplements is crucial for these individuals.

Severe deficiency can lead to life-threatening bleeding, such as internal bleeding or bleeding in the brain.

If a deficiency is suspected, a healthcare provider can order a blood test to measure levels.

Treatment typically involves taking supplements or increasing the intake of nutrient-rich foods.

Consulting with a healthcare provider is essential for proper diagnosis and treatment of deficiency.

Risks and side effects

Consuming this vitamin from food sources generally poses no risks or side effects.

However, high doses of supplements can interfere with the action of blood thinners, potentially increasing the risk of bleeding.

Blood thinners, such as warfarin, work by inhibiting the action of this nutrient to prevent blood clots.

Taking high doses of supplements can counteract this effect, reducing the medication's efficacy.

Individuals on blood thinners should carefully manage their intake under the guidance of a healthcare provider.

Sudden changes in levels can affect the balance between clotting and bleeding.

It's important to maintain a consistent intake from both food and supplements to avoid complications.

Before taking supplements, consult a healthcare provider, especially if you are on blood thinners or have a medical condition that increases the risk of bleeding.

A healthcare provider can help determine the appropriate dosage and monitor for potential interactions with other medications.

Vitamin K overdose  

Overdose is rare, as the body has a natural mechanism for regulating the amount it absorbs.

However, taking very high doses of supplements can lead to an overdose, which may cause symptoms such as nausea, diarrhea, and jaundice (yellowing of the skin and whites of the eyes).

In severe cases, an overdose can lead to more serious complications, such as liver damage.

Symptoms of an overdose may appear within a few hours to a few days after taking the supplements.

The severity of symptoms depends on the amount consumed and the individual's underlying health.

In severe cases, an overdose can lead to life-threatening complications, such as liver failure or coma.

If you suspect an overdose, seek medical attention immediately.

A healthcare provider can determine the appropriate treatment, which may involve medications to help remove excess amounts from the body or other supportive care.

Supplementation  

While it is generally safe to consume vitamin K from food sources, it is important to be mindful of your intake if you are taking blood thinners or have a medical condition that requires careful monitoring of your vitamin K intake.

If you are interested in taking a vitamin K supplement, but you are unsure of which one to take, you should read our article on the best vitamin K supplements available on the market.

This way, you can make an informed decision on which supplement is right for you and your needs.

Conclusion

This essential nutrient plays a crucial role in blood clotting and bone health.

It can be obtained from a variety of foods, including leafy green vegetables, fermented foods, and animal products.

While supplements can be beneficial in certain situations, it is important to consult with a healthcare provider before starting any supplement regimen.

Be aware of the potential risks and side effects, particularly if you are taking blood thinners or have a medical condition that affects levels.

Adequate intake is essential for optimal health and well-being.

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References

BSc, A. A., PhD. (2023, March 21). 20 foods that are high in vitamin K. Healthline. https://www.healthline.com/nutrition/foods-high-in-vitamin-k

Vitamin K. (2024, May 9). The Nutrition Source. https://nutritionsource.hsph.harvard.edu/vitamin-k/#:~:text=Vitamin%20K%20helps%20to%20make,to%20produce%20healthy%20bone%20tissue.

Morales-Brown, P. (2023, June 27). Health benefits and sources of vitamin K. https://www.medicalnewstoday.com/articles/219867#:~:text=Vitamin%20K%20benefits%20include%20supporting,blood%20clotting%20and%20bone%20metabolism.

Office of Dietary Supplements - Vitamin K. (n.d.). [4] https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/

Johnson, L. E. (2022, November 8). Vitamin K deficiency. MSD Manual Consumer Version. https://www.msdmanuals.com/home/disorders-of-nutrition/vitamins/vitamin-k-deficiency